Ab initio calculations including electron correlation, and mindo/3 calculations on the system C₂H⁺ ₇

Ab initio SCF and CEPA PNO calculations have been performed together with MINDO/3 calculations on the system C₂H⁺ ₇. In agreement with experimental assignment, but in contradiction to MINDO/3 results, the ab initio methods show the CC protonated structure to be more stable than the CH protonated structure. The energy difference is 8.5 kcal/mol at the SCF level and 6.3 kcal/mol with inclusion of electron correlation. Additionally, ΔH⁰ ₃₀₀ for the reaction C₂H⁺ _s + H₂ = C₂H⁺ ₇ and the proton affinity of ethane are computed.